Converting a .270 Weatherby to the WSM CAN BE DONE. However, it would be a pain/nightmare. If the barrel is a #1 or #2 and you shorten up the chamber to fit the length of the WSM, you may compromise the barrel distal to the receiver ring. Weatherby barrels avg. 1/3" of free bore space too. The WSM does not. This type of rechambering would take real precision work. Another problem is that the pilot bushing on the reamer has potential freedom during chambering because of the free bore space. Let alone you would most likely have feeding problems due to the longer action, unless your gunsmith uses feeding rails or a follower. You'd be better off, most likely, by buying a new barrel all together as opposed to paying a gunsmith to do all that work.